SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab3110535c1179549fa5c9ed4e91bf78f3bc79ccccf40aa721f5aaa0cc4e232f' 
  AND token = 'aDbg8kEPiFUgVn2ke+iKvAksU4sRogeDc4TIr+o0rnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}